Hydrofoil - Shaft Speed Guidance

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abracadabra - 16 Mar 2005 23:57 GMT

Preamble
=======

I am still trying to figure a way to get the propulsion
in place for my hydrofoil without it being bow-heavy.
I've looked at a number of ideas, but I haven't come
across anything better than what I see at the links
below.

http://www.sdp-si.com/D125/HTML/D125P5008.HTML
http://www.sdp-si.com/D125/HTML/D125P5008.HTML

However, their rated speed is 600 RPM !!!

Everything I've seen so far, gas/electric, seems to be
up in the 6000+ RPM range.

QUESTION
========

So here is my question ? What is the usual propeller speed
and motor speed for the model hydrofoils that have been
built/sold before ? Please indicate the boat's length and weight.

RPMp RPMm LENGTH WEIGHT

Keeping in mind that I would like to build the FHE-400,

http://boatdesign.net/gallery/showphoto.php/photo/1062
http://www.corrosion-doctors.org/Cases/BRAS-DOR.htm

I am thinking of fitting the above-mentionned gear-boxes
in the main foil fairings for foil-based props, like the original.

Thank you,

Eric

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William - 19 Mar 2005 05:30 GMT

> Preamble
> =======
[quoted text clipped - 9 lines]
>
> However, their rated speed is 600 RPM !!!

Yeah, they're not really designed for the kind of work you
want. You might have more luck putting together some
custom gear boxes using R/C car differential parts.
All you really need is a pair of miter gears of the same size
for a 1:1 ratio. Use ball bearings, and a good gear grease
and they'd probably do a better job. You can get "dogbone"
shafts and fittings, too, to give you a nice universal joint
arrangement.

A toothed belt drive might be even easier - use as many
idler rollers as needed to thread the belts from shaft to shaft
without rubbing on anything. Less vibration and cheaper.
(You'd might need some kind of access cover at the
bottom to facilitate belt replacement depending on how tight
things are.) -Wm

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abracadabra - 20 Mar 2005 16:50 GMT

Thank you. I will look into that.

Eric

> Yeah, they're not really designed for the kind of work you
> want. You might have more luck putting together some
[quoted text clipped - 11 lines]
> bottom to facilitate belt replacement depending on how tight
> things are.) -Wm

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aeronavale - 18 Apr 2005 04:54 GMT

Eric,

If one day you get you project of building the FHE-400 underway,
remember that the ship was not sold for metal and is still opened to
public visits in the "musee maritime du Quebec", (Quebec maritime
museum).

This is the museum site :http://www.mmq.qc.ca/parc.html where you will
find all the informations if one day you wish to see the real thing.

Signature

aeronavale

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Umi_Ryuzuki - 22 May 2005 16:39 GMT

Pods work, Ron Swart built his PHM using motor pods.
A simple stuffing tube would keep the water out.

http://home.wanadoo.nl/~hydrofoils1/phm.ht

--
Umi_Ryuzuk

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Model Forum / Radio Controlled / Water Models / May 2005

Hydrofoil - Shaft Speed Guidance